In computer vision, to obtain an ideal three-dimensional (3D) effect, relative positions between the cameras need to be determined. For example, a binocular stereo camera (referred to as a “binocular camera” for simplicity) or a multi-stereo camera (referred to as a “multi-camera” for simplicity) can be used to simultaneously photograph a standard calibration plate (e.g., a standard grid plate) for multiple times. To collect sufficient sample images, the posture and position of the calibration plate can be changed as much as possible. Therefore, this kind of calibration method might take a long time.